The present invention relates generally to electrical systems, such as for the distribution of power signals to controlled equipment, and particularly to a bus support system for such electrical systems.
Electrical systems with packaged electrical and electronic components are known and are in use. For example, motor control centers (MCCs) are used for power and data distribution in large and industrial operations. In a motor control center, a variety of components such as switchgear, semiconductor power electronic circuits, programmable logic controllers, motor controllers, and so forth are housed in large electrical enclosures that may be subdivided into compartments.
Typically, the MCC is connected to a main power line that feeds three-phase AC power into the MCC. The MCC includes associated bus bars, interconnections and supporting structures for distribution of electrical power to the various compartments. A typical arrangement includes vertical bus bars for each electrical phase of a multiple phase system which may include three power phases.
The vertical bus bars and other supporting structures should be able to withstand magnetic forces created by high circuit currents that pass through the MCC during a short circuit fault, or any other high current event. Typically, as the short circuit current flows through the bus bars, magnetic forces between adjacent bus bars act to move such bus bars laterally. Such movement of the bus bars must be prohibited to avoid damage within the MCC. Therefore, high short circuit current levels in the bus bars may require specially designed bus support structures with extensive bracing to withstand the high current levels. However, costs of manufacturing of such bus support system may be substantial.
Certain systems employ different bus support systems to withstand different levels of currents during operation. For example, a first bus support system may be employed for 42 kA and for 65 kA buses, and a different bus support system may be employed for 100 kA buses. However, this results in use of more material and expanded inventories, thereby substantially increasing the cost of the support system. Moreover, because fewer of the higher rated systems are typically made, the higher rated bus support systems do not benefit from the same economy of scale as do the lower rated support systems.
Accordingly, it would be desirable to develop a bus support system that provides sufficient strength to withstand high currents associated with short-circuits in an electrical system.